The invention concerns control systems for gas turbine engines.
In a gas turbine engine used to power an aircraft, malfunctions sometimes occur. While many malfunctions are minor, some are significant enough to reduce thrust of the engine to a large degree. For example, if the engine ingests a large bird, damage can occur which significantly compromises the thrust-producing ability of the engine. As another example, a missile fired by a terrorist can produce similar damage, or worse. As a third example, during take-off, the engine can ingest debris left on a runway.
In such cases, the pilot can take at least two strategies. One is to continue operation of the engine, but at the reduced thrust level. The second is to shut down the engine. The invention provides another strategy for operating a malfunctioning gas turbine engine.
In one form of the invention, a system detects damage in a gas turbine engine, as by detecting a lower-than-expected amount of thrust. When the damage is detected, the invention then takes measures to exchange (1) future lifetime of the engine for (2) present thrust.
For example, the invention may increase a limit on speed of a particular rotor, which consumes lifetime of the rotor and other components, but produces larger thrust presently. As another example, a limit on turbine inlet temperature may be raised, which again consumes lifetime of components, but produces larger thrust presently.